Epoxy Bass Bridge Repair

[Gregor _]

Terry,

what do you mean by "you need to leave some epoxy in the gap. You 
don’t want to epoxy-starve the joint."?

I found a source for Western System Epoxy handy repair set including that filler here in Germany. Good to know, I will try it perhaps one day, but not with that Kawai. I told the customer to ask a collegue who has 7 pianotechs working for his shop: 4 on master level, 2 with certificate of apprenticeship and one apprentice, and they have a huge workshop. I don´t do repairs with woodwork anymore, just tuning, small repairs and selling pianos. But in this case it probably would have been easier to order a new brigde from Kawai which fits perfectly without any adjusting: just installing and it fits.

Gregor

From: mfarrel2 at tampabay.rr.com
To: pianotech at ptg.org
Subject: Re: Epoxy Bass Bridge Repair
Date: Fri, 9 May 2008 08:57:04 -0400











Epoxy repairs for a situation as you describe can 
yield very good results. Sometimes the crack 
opens up a fair bit – you’ll want to clamp it back into position – not to clamp in the traditional sense, but rather to simply 
position the parts in their original orientation 
– you need to leave some epoxy in the gap. You 
don’t want to epoxy-starve the joint.
 
I use West System epoxy resin, hardeners and 
fillers:
www.westsystem.com My favorite for a 
cracked bridge is #404 High-Density Filler and 
using the West System two-step bonding procedure described on the West System 
web site. The following is from the West System web site:
 
404 High-Density Filler
404 High-Density filler is a thickening additive developed for maximum
physical properties in hardware bonding where high-cyclic loads are
anticipated. It can also be used for filleting and gap filling where 
maximum
strength is necessary. Color: off-white.
 
You can either push the bridge pins into 
the uncured epoxy, tidy up and be done with it, or, for a neater, more 
exacting job, you can epoxy the gap and then drill bridge pin holes after the 
epoxy hardens. I have found that if cosmetic considerations are not paramount, I 
apply the epoxy, clamp together until the wood is close to original dimension, 
clean off epoxy squeeze out (acetone) - at that point you will be able to see 
the outline of the original pin holes - push pins in place - the wood will have 
been drawn together enough to hold the pin in its original position - and then 
level off and clean up the little bit of epoxy that squeezes out of the holes as 
you push the pin in place. Wait a day or two for the epoxy to completely cure, 
go back and install bass strings.
 
I've done this repair numerous times with great 
success.
 
And of course, on a nicer piano where the budget 
allows, new bridge and/or new cap is preferred.
 
Terry Farrell

  ----- Original Message ----- 
  From: 
  Gregor 
  _ 
  To: pianotech at ptg.org 
  Sent: Friday, May 09, 2008 5:13 AM
  Subject: Epoxy Bass Bridge Repair
  
I crawled the archieves but I did not really find what I was 
  looking for: does Epoxy work even for bigger gaps?

I wanted to tune a 
  Kawai CE-11 upright yesterday but the bass bridge looked horrible: a long gap 
  which affected 9 notes. The gap started at the upper pin row and the pins were 
  vertical. Some strings rattled at the pins. The gap expanded up to 4 mm above 
  the upper pin row. I did not try but I could imagine that I could have pulled 
  out some pins without using pliers.

First at all: I never worked with 
  Epoxy. My first thought was to pull out the pins, fill the gap with epoxy and 
  drill new holes for new pins. Could that work or is such a gap too much for 
  Epoxy? The bridge is made of one piece of wood, no cap.

I was shocked 
  about such a gap in a Kawai from 1992 (no grey market import): no floor 
  heating, no air con and no heater near by the piano. And I don´t live in an 
  area with huge differences in the climate. Very strange. That damage is a 
  pitty because everything else in this piano was in a pretty good condition. 
  But making a new bridge would be definitely too expensive including transports 
  from the second floor into a workshop and back to the 
  customer.

Gregor


  
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